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Visual Glossary

Basalt dikes cut across granite along the Klondike Highway in Klondike Gold Rush National Historical Park Basalt dikes cut across granite along the Klondike Highway in Klondike Gold Rush National Historical Park.

Dikes

Dikes are sheet-like or tabular igneous intrusions that cut across sedimentary layering, metamorphic foliation, or other texture of a pre-existing rock.

The dikes shown in the photograph above are made of basalt that was injected while still molten into older granites.

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